Ultrasound diagnostic apparatus, method for controlling ultrasound diagnostic apparatus, and program for controlling ultrasound diagnostic apparatus

ABSTRACT

An ultrasound diagnostic apparatus  1  includes an image acquisition unit  3  that generates an ultrasound image, an image recognition unit  9  that performs image recognition for the ultrasound image to calculate recognition scores, an index value calculation unit  10  that calculates index values of a plurality of parts on the basis of the recognition scores calculated for a predetermined number of ultrasound images, an order decision unit  11  that decides a determination order in which part determination is performed for the plurality of parts on the basis of the index values, and a part determination unit  12  that determines an imaging part of a subject on the basis of the recognition scores calculated according to the determination order.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2018/001326 filed on Jan. 18, 2018, which claims priority under 35U.S.C. § 119(a) to Japanese Patent Application No. 2017-016590 filed onFeb. 1, 2017. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an ultrasound diagnostic apparatus, amethod for controlling an ultrasound diagnostic apparatus, and a programfor controlling an ultrasound diagnostic apparatus, and moreparticularly, to an ultrasound diagnostic apparatus that determines animaging part of a subject, a method for controlling the ultrasounddiagnostic apparatus, and a program for controlling the ultrasounddiagnostic apparatus.

2. Description of the Related Art

In recent years, an ultrasound diagnostic apparatus has been known as anapparatus for obtaining an image of the inside of a subject. In general,the ultrasound diagnostic apparatus comprises an ultrasound probecomprising a transducer array in which a plurality of elements arearranged. In a state in which the ultrasound probe is in contact withthe body surface of the subject, ultrasound beams are transmitted fromthe transducer array to the subject and the transducer array receivesultrasound echoes from the subject. In this way, element data isacquired. In addition, the ultrasound diagnostic apparatus electricallyprocesses the obtained element data to generate an ultrasound image of acorresponding part of the subject.

It has been known that, in a case in which the ultrasound image of apart of the subject is generated by the ultrasound diagnostic apparatus,there are imaging conditions suitable for each part. It is preferablethat the imaging conditions are automatically set in a case in which theultrasound image of each part is generated. However, it is necessary toautomatically determine an imaging part of the subject which iscurrently being examined in order to automatically set the imagingconditions.

Therefore, various proposals have been made as the ultrasound diagnosticapparatus that can automatically determine an imaging part of a subject.For example, an ultrasound diagnostic apparatus disclosed inJP1992-224738A (JP-H04-224738A) includes a pattern memory that storescharacteristic patterns of each part of a subject, collates an imagepattern extracted from a generated ultrasound image with a plurality ofpattern data items stored in the pattern memory, detects pattern datasimilar to the image pattern included in the generated ultrasound image,and determines an imaging part.

SUMMARY OF THE INVENTION

However, in general, the amount of calculation load required for imagerecognition that extracts an image pattern from a generated ultrasoundimage and collates the extracted image pattern with pattern data storedin advance is large. In particular, in a case in which the imagerecognition is performed by an apparatus with a low processingperformance, it takes a lot of time until the image recognition iscompleted. In addition, in the ultrasound diagnostic apparatus disclosedin JP1992-224738A (JP-H04-224738A), in a case in which the imagerecognition is performed for a plurality of parts of the subject, it isnecessary to collate the image pattern extracted from the generatedultrasound image with many pattern data items corresponding to theplurality of parts. As a result, the time required to determine theimaging part further increases. In addition, in the ultrasounddiagnostic apparatus disclosed in JP1992-224738A (JP-1104-224738A), thisprocess needs to be performed for each of the plurality of parts of thesubject.

The invention has been made in order to solve the problems of therelated art and an object of the invention is to provide an ultrasounddiagnostic apparatus that can reduce the time required to determine animaging part, a method for controlling the ultrasound diagnosticapparatus, and a program for controlling the ultrasound diagnosticapparatus.

In order to achieve the object, an ultrasound diagnostic apparatusaccording to the invention comprises: an image acquisition unit thattransmits an ultrasound beam from an ultrasound probe to a subject togenerate an ultrasound image; an image recognition unit that performsimage recognition for the ultrasound image generated by the imageacquisition unit to calculate recognition scores of a plurality of partsof the subject; an index value calculation unit that calculates indexvalues of the plurality of parts on the basis of the recognition scoresof the plurality of parts calculated for a predetermined number ofultrasound images; an order decision unit that decides a determinationorder in which part determination is performed for the plurality ofparts on the basis of the index values; and a part determination unitthat determines an imaging part of the subject on the basis of therecognition scores calculated by the image recognition unit according tothe determination order.

Preferably, the index value calculation unit uses, as the index valuesof the plurality of parts, recognition scores of the plurality of partscalculated by the image recognition unit for a latest ultrasound imageacquired by the image acquisition unit.

The index value calculation unit may calculate the index values of theplurality of parts of the subject on the basis of recognition scores ofthe plurality of parts calculated by the image recognition unit for eachof a plurality of ultrasound images which are continuously acquired intime series and include a latest ultrasound image acquired by the imageacquisition unit.

Preferably, the index value calculation unit uses mean values or mediansof the recognition scores of the plurality of parts calculated for theplurality of ultrasound images as the index values of the plurality ofparts.

The index value calculation unit may use maximum values or minimumvalues of the recognition scores of the plurality of parts calculatedfor the plurality of ultrasound images as the index values of theplurality of parts.

The index value calculation unit may calculate weighted mean values ofthe recognition scores of the plurality of parts by giving a largerweight to an ultrasound image more recently acquired by the imageacquisition unit among the plurality of ultrasound images and may usethe weighted mean values as the index values of the plurality of parts.

The index value calculation unit may give ranking scores to theplurality of parts for each of the plurality of ultrasound images suchthat the part with a higher recognition score has a higher ranking scoreand may use sums of the ranking scores of the plurality of parts for theplurality of ultrasound images as the index values of the plurality ofparts.

The index value calculation unit may have a threshold value of therecognition score and may use the number of recognition scores greaterthan the threshold value among the recognition scores of the pluralityof parts calculated for the plurality of ultrasound images as the indexvalue of each of the plurality of parts.

Preferably, in a case in which there are the same index values among thecalculated index values of the plurality of parts, the index valuecalculation unit calculates the index values again, using an ultrasoundimage group which includes the latest ultrasound image and consists ofultrasound images which are continuous in time series and whose numberis less than the number of the ultrasound images used to calculate theindex values.

In a case in which there are the same index values among the calculatedindex values of the plurality of parts, the index value calculation unitmay calculate the index values again, using an ultrasound image groupconsisting of a plurality of ultrasound images which are continuous intime series and are acquired by the image acquisition unit before thelatest ultrasound image in time series.

Preferably, the ultrasound diagnostic apparatus further comprises aprobe state detection unit that detects a change in the imaging partcaused by movement of the ultrasound probe. Preferably, after the probestate detection unit detects the change in the imaging part, the indexvalue calculation unit starts to calculate the index value.

Preferably, the order decision unit decides the determination order suchthat the part with a larger index value ranks higher.

According to the invention, there is provided a method for controllingan ultrasound diagnostic apparatus. The method comprises: transmittingan ultrasound beam from an ultrasound probe to a subject to generate anultrasound image; performing image recognition for the ultrasound imageto calculate recognition scores of a plurality of parts of the subject;calculating index values of the plurality of parts on the basis of therecognition scores of the plurality of parts calculated for apredetermined number of ultrasound images; deciding a determinationorder in which part determination is performed for the plurality ofparts on the basis of the index values; and determining an imaging partof the subject on the basis of the recognition scores calculatedaccording to the determination order.

According to the invention, there is provided a program for controllingan ultrasound diagnostic apparatus. The program comprises: a step oftransmitting an ultrasound beam from an ultrasound probe to a subject togenerate an ultrasound image; a step of performing image recognition forthe ultrasound image to calculate recognition scores of a plurality ofparts of the subject; a step of calculating index values of theplurality of parts on the basis of the recognition scores of theplurality of parts calculated for a predetermined number of ultrasoundimages; a step of deciding a determination order in which partdetermination is performed for the plurality of parts on the basis ofthe index values; and a step of determining an imaging part of thesubject on the basis of the recognition scores calculated according tothe determination order.

According to the invention, the ultrasound diagnostic apparatus includesthe order decision unit that decides the determination order in whichpart determination is performed and determines an imaging part on thebasis of the determination order. Therefore, it is possible to reducethe time required to determine the imaging part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the configuration of anultrasound diagnostic apparatus according to Embodiment 1 of theinvention.

FIG. 2 is a block diagram illustrating the internal configuration of areceiving unit illustrated in FIG. 1.

FIG. 3 is a block diagram illustrating the internal configuration of animage generation unit illustrated in FIG. 1.

FIG. 4 is a flowchart illustrating an operation of the ultrasounddiagnostic apparatus according to Embodiment 1 of the invention.

FIG. 5 is a flowchart illustrating a part determination operation of theultrasound diagnostic apparatus according to Embodiment 1 of theinvention.

FIG. 6 is a flowchart illustrating an operation of an ultrasounddiagnostic apparatus according to Embodiment 2 of the invention.

FIG. 7 is a flowchart illustrating a part determination operation of anultrasound diagnostic apparatus according to Embodiment 3 of theinvention.

FIG. 8 is a block diagram illustrating the configuration of anultrasound diagnostic apparatus according to Embodiment 4 of theinvention.

FIG. 9 is a flowchart illustrating a part determination operation of theultrasound diagnostic apparatus according to Embodiment 4 of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 illustrates the configuration of an ultrasound diagnosticapparatus according to Embodiment 1 of the invention. An ultrasounddiagnostic apparatus 1 comprises an ultrasound probe 2 provided with atransducer array 2A. A display control unit 7 and a display unit 8 aresequentially connected to the ultrasound probe 2 through an imageacquisition unit 3.

The image acquisition unit 3 includes a receiving unit 4 and atransmitting unit 5 that are connected to the transducer array 2A of theultrasound probe 2, and an image generation unit 6 that is connected tothe receiving unit 4. The display control unit 7 is connected to theimage generation unit 6. In addition, an image recognition unit 9 isconnected to the image generation unit 6. An index value calculationunit 10 is connected to the image recognition unit 9. An order decisionunit 11 is connected to the index value calculation unit 10. A partdetermination unit 12 is connected to the order decision unit 11.Further, the image recognition unit 9 is connected to the partdetermination unit 12. Furthermore, a probe state detection unit 13 isconnected to the image generation unit 6.

In addition, an apparatus control unit 14 is connected to the imageacquisition unit 3, the display control unit 7, the image recognitionunit 9, the index value calculation unit 10, the order decision unit 11,the part determination unit 12, and the probe state detection unit 13.An operation unit 15 and a storage unit 16 are connected to theapparatus control unit 14. The apparatus control unit 14 and the storageunit 16 are connected such that information can be bi-directionallytransmitted and received therebetween.

The transducer array 2A of the ultrasound probe 2 illustrated in FIG. 1includes a plurality of elements (ultrasound transducers) which areone-dimensionally or two-dimensionally arranged. Each of the elementstransmits ultrasonic waves in response to a driving signal supplied fromthe transmitting unit 5. In addition, each of the elements receivesultrasound echoes from a subject and outputs a received signal. Each ofthe elements is, for example, a transducer in which electrodes areformed at both ends of a piezoelectric body made of piezoelectricceramic typified by lead zirconate titanate (PZT), a polymerpiezoelectric element typified by polyvinylidene difluoride (PVDF), or apiezoelectric single crystal typified by lead magnesium niobate-leadtitanate (PMN-PT).

In a case in which a pulsed voltage or a continuous-wave voltage isapplied to the electrodes of the transducer, the piezoelectric body isexpanded and contracted and pulsed or continuous ultrasonic waves aregenerated from each transducer. The ultrasonic waves are combined toform an ultrasound beam. In addition, each transducer receivespropagated ultrasonic waves, is expanded and contracted, and generatesan electric signal. The electric signal is output as a receivedultrasound signal from each transducer to the receiving unit 4.

As illustrated in FIG. 2, the receiving unit 4 of the image acquisitionunit 3 has a configuration in which an amplification unit 17 and ananalog/digital (A/D) conversion unit 18 are connected in series to eachother. The receiving unit 4 outputs, to the image generation unit 6,element data obtained by amplifying the received signal output from eachelement of the transducer array 2A with the amplification unit 17 andconverting the amplified signal into a digital signal with the A/Dconversion unit 18.

The transmitting unit 5 of the image acquisition unit 3 includes, forexample, a plurality of pulse generators, adjusts the amount of delay ofeach driving signal such that the ultrasonic waves transmitted from theplurality of elements of the transducer array 2A form an ultrasoundbeam, on the basis of a transmission delay pattern selected according toa control signal from the apparatus control unit 14, and supplies thedriving signals to the plurality of elements.

As illustrated in FIG. 3, the image generation unit 6 of the imageacquisition unit 3 has a configuration in which a brightness-mode(B-mode) processing unit 19 and an image processing unit 20 aresequentially connected in series to each other.

The B-mode processing unit 19 performs a reception focusing processwhich applies a delay to each element data item following a set soundspeed on the basis of a reception delay pattern selected according to acontrol signal from the apparatus control unit 14 and adds the receiveddata (phasing addition). A sound ray signal in which the focus of theultrasound echo is narrowed is generated by the reception focusingprocess. In addition, the B-mode processing unit 19 corrects theattenuation of the sound ray signal caused by a propagation distanceaccording to the depth of the reflection position of ultrasonic wavesand then performs an envelope detection process to generate a B-modeimage signal which is tomographic image information related to thetissues in the subject. The B-mode image signal generated by the B-modeprocessing unit 19 is output to the image processing unit 20.

The image processing unit 20 converts the B-mode image signal generatedby the B-mode processing unit 19 into an image signal based on a generaltelevision signal scanning system (raster conversion), performs varioustypes of necessary image processing, such as a gradation process, forthe B-mode image signal, and outputs a B-mode image signal, that is, anultrasound image to the display control unit 7 and the image recognitionunit 9.

As illustrated in FIG. 1, the display control unit 7 of the ultrasounddiagnostic apparatus 1 directs the display unit 8 to display theultrasound image on the basis of the B-mode image signal acquired by theimage acquisition unit 3.

The display unit 8 includes a display device, such as a liquid crystaldisplay (LCD), and displays the ultrasound image under the control ofthe apparatus control unit 14.

The image recognition unit 9 receives the ultrasound image subjected tovarious types of image processing from the image processing unit 20 ofthe image generation unit 6 and performs image recognition, such aspattern recognition, for the ultrasound image to calculate recognitionscores of a plurality of parts of the subject. Here, the recognitionscores of the plurality of parts of the subject are the similarities ofimaging parts in the ultrasound image to the plurality of parts of thesubject. As the value of the similarity becomes larger, the probabilityof the imaging part in the ultrasound image being the corresponding partbecomes higher.

The index value calculation unit 10 calculates the index values of theplurality of parts of the subject on the basis of the recognition scoresof the plurality of parts of the subject calculated by the imagerecognition unit 9. There are various methods for calculating the indexvalues. Hereinafter, for the purpose of description, it is assumed thatthe index values of the plurality of parts of the subject are the meanvalues of the recognition scores of the plurality of parts of thesubject calculated for a plurality of ultrasound images. As such, in acase in which the index values are calculated on the basis of therecognition scores for a plurality of ultrasound images, the index valuecalculation unit 10 calculates the index values on the basis of therecognition scores for a plurality of ultrasound images which arecontinuously acquired in time series and include the latest ultrasoundimage acquired by the image acquisition unit 3.

The order decision unit 11 decides a determination order in whichimaging part determination is performed for the plurality of parts ofthe subject on the basis of the index values of the plurality of partsof the subject calculated by the index value calculation unit 10. Atthat time, the order decision unit 11 decides the determination ordersuch that a part with a high probability of being the imaging part whoseimage is currently captured ranks higher.

The part determination unit 12 determines the imaging part of thesubject for the ultrasound image acquired by the image acquisition unit3 on the basis of the recognition scores calculated by the imagerecognition unit 9 according to the determination order. That is, thepart determination unit 12 sequentially determines the imaging part fromthe part that ranks first among the plurality of parts of the subjectaccording to the determination order decided by the order decision unit11.

The probe state detection unit 13 determines whether the ultrasoundprobe 2 is in an aerial emission state. Here, the aerial emission stateof the ultrasound probe 2 means a state in which the ultrasound probe 2is separated from the body surface of the subject and the ultrasoundbeam transmitted from the transducer array 2A to the subject is emittedto the air. In a case in which the ultrasound probe 2 is in the aerialemission state, the ultrasound beam emitted from the transducer array 2Ais not reflected from a part of the subject and the received signalgenerated in the transducer array 2A does not have sufficient intensity.As a result, the image of the part is not included in the ultrasoundimage generated by the image generation unit 6. Therefore, the probestate detection unit 13 determines that the ultrasound probe 2 is in theaerial emission state in a case in which no image is included in theultrasound image and determines that the ultrasound probe 2 is incontact with the subject in a case in which an image is included in theultrasound image.

The apparatus control unit 14 controls each unit of the ultrasounddiagnostic apparatus 1 on the basis of commands input by an operatorthrough the operation unit 15.

The operation unit 15 is used by the operator to perform an inputoperation and may include, for example, a keyboard, a mouse, atrackball, and a touch panel.

The storage unit 16 stores, for example, an operation program of theultrasound diagnostic apparatus 1 and may be a recording medium, such asa hard disc drive (HDD), a solid state drive (SSD), a flexible disc(FD), a magneto-optical (MO) disc, a magnetic tape (MT), a random accessmemory (RAM), a compact disc (CD), a digital versatile disc (DVD), asecure digital (SD) card, or a universal serial bus (USB) memory, or aserver.

The image generation unit 6 of the image acquisition unit 3, the displaycontrol unit 7, the image recognition unit 9, the index valuecalculation unit 10, the order decision unit 11, the part determinationunit 12, the probe state detection unit 13, and the apparatus controlunit 14 are implemented by a central processing unit (CPU) and a controlprogram that causes the CPU to perform various processes. However, theseunits may be implemented by a digital circuit and a computer. Inaddition, some or all of the image generation unit 6, the displaycontrol unit 7, the image recognition unit 9, the index valuecalculation unit 10, the order decision unit 11, the part determinationunit 12, the probe state detection unit 13, and the apparatus controlunit 14 may be integrated into one CPU.

Next, the operation of the ultrasound diagnostic apparatus 1 accordingto Embodiment 1 will be described with reference to a flowchartillustrated in FIG. 4.

First, in Step S 1, the receiving unit 4 and the transmitting unit 5 ofthe image acquisition unit 3 perform the transmission and reception ofultrasound beams and scanning, that is, the capture of an ultrasoundimage, using the plurality of ultrasound transducers of the transducerarray 2A in the ultrasound probe 2. At that time, each ultrasoundtransducer which has received ultrasound echoes from the subjectgenerates a received signal and the received signal is input to thereceiving unit 4. The amplification unit 17 of the receiving unit 4amplifies the received signal input to the receiving unit 4. Inaddition, the A/D conversion unit 18 performs A/D conversion for thereceived signal. Furthermore, the received signal is input to the imagegeneration unit 6. The B-mode processing unit 19 of the image generationunit 6 generates a B-mode image, that is, an ultrasound image.

Then, in Step S2, the probe state detection unit 13 determines whetherthe ultrasound probe 2 is in the aerial emission state. In a case inwhich it is determined in Step S2 that the ultrasound probe 2 is in theaerial emission state, the process returns to Step S1. On the otherhand, in a case in which it is determined in Step S2 that the ultrasoundprobe 2 is not in the aerial emission state and is in contact with thebody surface of the subject, the process proceeds to Step S3.

In Step S3, the imaging part that is currently being examined isdetermined. The part determination in Step S3 will be described indetail below with reference to FIG. 5.

In a case in which the imaging part is determined in Step S3, theprocess proceeds to Step S4. In Step S4, the apparatus control unit 14sets imaging conditions suitable for the part determined in Step S3.Here, the imaging conditions include, for example, a frame rate inultrasound diagnosis, the resolution of an ultrasound image, thebrightness of an ultrasound image, and a dynamic range in ultrasounddiagnosis.

Then, in Step S5, the image acquisition unit 3 acquires an ultrasoundimage. At that time, since the imaging conditions set in Step S4 areused as the imaging conditions, the image acquisition unit 3 can acquirethe ultrasound image in which the image of the imaging part is clear.

Then, in Step S6, it is determined again whether the ultrasound probe 2is in the aerial emission state. Here, in a case in which the probestate detection unit 13 determines that the ultrasound probe 2 is not inthe aerial emission state and is in contact with the body surface of thesubject, it is determined that the imaging part has not been changed andthe process returns to Step S5 to acquire an ultrasound image again. Onthe other hand, in a case in which the probe state detection unit 13determines that the ultrasound probe 2 is in the aerial emission state,it is determined that a change in the imaging part has started and theprocess returns to Step S1.

Next, the part determination in Step S3 will be described with referenceto FIG. 5. In a case in which the part determination in Step S3 starts,first, an ultrasound image is acquired in Step S7.

Then, in Step S8, the image recognition unit 9 calculates therecognition scores of a plurality of parts of the subject for theultrasound image acquired in Step S7.

Then, in Step S9, the apparatus control unit 14 determines whether therecognition scores of a plurality of parts of the subject have beencalculated for a predetermined number of frames of ultrasound images.Here, the part determination process in Step S3 has the determinationstep of Step S9 in order to obtain the number of recognition scoresrequired for the index value calculation unit 10 to calculate the indexvalues. Therefore, in a case in which it is determined in Step S9 thatthe recognition scores have not been calculated for a predeterminednumber of frames of ultrasound images, the process returns to Step S7 toacquire an ultrasound image. Then, in Step S8, a new recognition scoreis calculated. As such, in a case in which it is determined in Step S9that the recognition scores of a plurality of parts of the subject havebeen calculated for a predetermined number of frames of ultrasoundimages after the repetition of Steps S7 and S8, the process proceeds toStep S10.

In Step S10, the index value calculation unit 10 averages apredetermined number of recognition scores calculated by the repetitionof Steps S7 and S8 for each of a plurality of parts to calculate theindex values of the plurality of parts of the subject.

Then, in Step S11, the order decision unit 11 decides the determinationorder of the plurality of parts of the subject such that, as the indexvalues of the plurality of parts of the subject calculated in Step S10become larger, the rankings become higher. For example, in a case inwhich the plurality of parts of the subject include the heart and thelung, the heart has the largest index value, and the lung has the secondlargest index value, the heart ranks first and the lung ranks second.

Then, in Step S12, in a case in which the image acquisition unit 3acquires a new ultrasound image, the process proceeds to Step S13.

In Step S13, the image recognition unit 9 calculates the recognitionscore of the part that ranks first according to the determination orderdecided in Step S 11 for the latest ultrasound image acquired in StepS12. For example, in a case in which the heart ranks first in thedetermination order, only the recognition score of the heart iscalculated for the ultrasound image acquired in Step S12.

Then, in Step S14, the part determination unit 12 performs thresholdvalue determination of whether the recognition score of one partcalculated in Step S13 is greater than a determination threshold value.The determination threshold value is the threshold value of therecognition score in part determination and the same determinationthreshold value can be used for all of the parts. In a case in which itis determined in Step S14 that the recognition score of one part isequal to or less than the determination threshold value, it isdetermined that it is difficult to decide the imaging part as the partwhose recognition score has been calculated in Step S13 and the processproceeds to Step S15.

In Step S15, the apparatus control unit 14 determines whether thethreshold value determination for the recognition scores of all of theplurality of parts of the subject has been completed in Step S14. In acase in which it is determined in Step S15 that the threshold valuedetermination for the recognition scores of all of the plurality ofparts of the subject has not been completed in Step S14, the processproceeds to Step S16.

In Step S16, the apparatus control unit 14 updates a determination part.That is, the apparatus control unit 14 changes the part whoserecognition score is to be calculated in the next Step S13 from the partthat ranks first to the part that ranks second in the determinationorder decided in Step S11. Hereinafter, for the purpose of description,among the parts of the subject which rank according to the determinationorder decided in Step S11, the part to be determined to be the imagingpart, that is, the part to be determined in Step S14 is referred to asthe determination part. In a case in which the determination part isupdated, the process returns to Step S13 in order to determine theimaging part for the next part on the basis of the determination order.

In Step S13 performed for the second time, only the recognition score ofthe part that ranks second in the determination order decided in StepS11 is calculated for the ultrasound image acquired in Step S12. Then,in Step S14, the part determination unit 12 determines whether therecognition score of the part that ranks second in the determinationorder is greater than the determination threshold value. Here, in a casein which it is determined that the recognition score is equal to or lessthan the determination threshold value, the process proceeds to StepS15.

As such, as long as it is determined in Step S14 that the recognitionscore of the determination part is equal to or less than thedetermination threshold value, Steps S13 to S16 are repeated accordingto the determination order decided in Step S11. In a case in which it isdetermined in Step S15 that the threshold value determination for therecognition scores of all of the plurality of parts of the subject hasbeen completed in Step S14 as a result of the repetition of Steps S13 toS16, it is determined that it is difficult to decide the part includedin the ultrasound image acquired in Step S12 to be any of the pluralityof parts of the subject and the process returns to Step S8. In thesubsequent Steps S8 to S14, the index values of the plurality of partsof the subject are newly calculated on the basis of the newly calculatedrecognition scores of the plurality of parts of the subject and a newdetermination order is decided on the basis of the index values. Inaddition, the recognition scores are calculated for the ultrasound imagenewly acquired in Step S12 according to the newly decided determinationorder and part determination is performed for the imaging part on thebasis of the recognition scores.

In a case in which it is determined in Step S14 that the recognitionscore of the determination part is greater than the determinationthreshold value, the process proceeds to Step S17.

In Step S17, the part determination unit 12 decides the imaging partwhose image is currently captured to be the determination part havingthe recognition score determined to be greater than the determinationthreshold value in Step S14. Then, the part determination operationends.

The ultrasound diagnostic apparatus 1 according to the above-describedEmbodiment 1 decides the determination order such that the part with ahigh probability of being the imaging part whose image is currentlycaptured ranks higher and sequentially determines a plurality of partsof the subject according to the determination order in a case in whichpart determination is performed. Therefore, it is possible to reduce thecalculation load of the ultrasound diagnostic apparatus 1 and to reducethe time required to determine the imaging part.

The index value calculation unit 10 averages the recognition scores ofthe plurality of parts of the subject calculated for a plurality ofultrasound images to calculate the index values of the plurality ofparts of the subject. However, for example, the number of ultrasoundimages required for the index value calculation unit 10 to calculate theindex value may be set by the operator through the operation unit 15 orthe like, or may be stored in the index value calculation unit 10 andthe storage unit 16 in advance.

In addition, the index value calculation unit 10 may calculate the indexvalue using various methods other than the method of averaging therecognition scores of each of the plurality of parts of the subject. Forexample, the index value calculation unit 10 may use the medians of therecognition scores of the plurality of parts of the subject calculatedfor a plurality of ultrasound images as the index values of theplurality of parts of the subject.

In addition, for example, the index value calculation unit 10 may usethe maximum values of the recognition scores of the plurality of partsof the subject calculated for a plurality of ultrasound images as theindex values of the plurality of parts of the subject. Further, theindex value calculation unit 10 may use the minimum values of therecognition scores of the plurality of parts of the subject calculatedfor a plurality of ultrasound images as the index values of theplurality of parts of the subject.

Furthermore, for example, the index value calculation unit 10 may useweighted mean values obtained by weighting and averaging the recognitionscores of the plurality of parts of the subject calculated for aplurality of ultrasound images as the index values of the plurality ofparts of the subject. In this case, the index value calculation unit 10may calculate the weighted mean value by giving a larger weight to therecognition score calculated for an ultrasound image more recentlyacquired by the image acquisition unit 3 among the plurality ofultrasound images.

For example, the index value calculation unit 10 may give ranking scoresto a plurality of parts of the subject for each of a plurality ofultrasound images such that the ranking score becomes higher as therecognition score becomes higher. In this case, the index valuecalculation unit 10 can use the sums of the ranking scores of theplurality of parts of the subject for the plurality of ultrasound imagesas the index values of the plurality of parts of the subject. That is,for example, for each ultrasound image, the ranking scores are given tothe plurality of parts of the subject such that a higher score is givento the part with a higher recognition score in the order of five points,four points, three points, two points, and one point and the rankingscores of each part for the plurality of ultrasound images are added upto calculate the index values of the plurality of parts of the subject.

In addition, for example, the index value calculation unit 10 may have athreshold value of the recognition score and calculate the index valuefrom the result of threshold value determination for the recognitionscore. In this case, the index value calculation unit 10 can use thenumber of recognition scores that are greater than the threshold valueamong the recognition scores of the plurality of parts of the subjectcalculated for the plurality of ultrasound images as the index values ofthe plurality of parts of the subject. That is, for example, in a casein which the number of recognition scores that are greater than thethreshold value among the recognition scores of the heart calculated fora plurality of ultrasound images is 3, the index value calculation unit10 can set the index value of the heart to 3.

As described above, the index value calculation unit 10 can calculatethe index values on the basis of the recognition scores calculated for aplurality of frames of ultrasound images. However, the index valuecalculation unit 10 may use the recognition scores calculated for oneframe of ultrasound image as the index values. For example, the indexvalue calculation unit 10 can use the recognition scores of a pluralityof parts of the subject calculated only for the latest ultrasound imageacquired by the image acquisition unit 3 as the index values of theplurality of parts of the subject.

In addition, in a case in which there are the same index values amongthe calculated index values of the plurality of parts of the subject,the index value calculation unit 10 may calculate the index valuesagain. In this case, the index value calculation unit 10 can calculatethe index values again, using the recognition scores calculated for anultrasound image group that includes the latest ultrasound imageacquired by the image acquisition unit 3 and consists of ultrasoundimages whose number is less than the number of ultrasound images used ina case in which the same index values have been calculated. It ispreferable that the ultrasound image group used here is continuouslyacquired in time series by the image acquisition unit 3.

In addition, in a case in which the index values are calculated again,the index value calculation unit 10 may calculate the index values,using the recognition scores calculated for an ultrasound image groupconsisting of a plurality of ultrasound images that are acquired by theimage acquisition unit 3 before the latest ultrasound image in timeseries and are continuous in time series.

In the above-described embodiment, in a case in which no image isincluded in the acquired ultrasound image, the probe state detectionunit 13 determines that the ultrasound probe 2 is in the aerial emissionstate. However, the probe state detection unit 13 may compare aplurality of ultrasound images acquired in time series to determinewhether the ultrasound probe 2 is in the aerial emission state. That is,the probe state detection unit 13 may compare a plurality of ultrasoundimages acquired in time series and may determine that the ultrasoundprobe 2 is not in contact with the body surface and is in the aerialemission state in a case in which there is no change in the imagesincluded in the plurality of ultrasound images between the plurality ofultrasound images. In addition, in a case in which there is a change inthe images included in the plurality of ultrasound images acquired intime series between the plurality of ultrasound images, the probe statedetection unit 13 may determine that a part of the subject is includedin the plurality of ultrasound images and the ultrasound probe 2 is incontact with the body surface of the subject.

With this configuration, even in the case in which ultrasonography gelis attached to the ultrasound probe 2, the probe state detection unit 13can compare a plurality of ultrasound images acquired in time series todetermine whether the ultrasound probe 2 is in the aerial emissionstate.

In the flowchart illustrated in FIG. 4, in a case in which the probestate detection unit 13 detects a change in the imaging part, the partdetermination in Step S3 starts. This means that, in a case in which theprobe state detection unit 13 detects a change in the imaging part, theindex value calculation unit 10 starts to calculate the index value onthe basis of the recognition score calculated for a newly acquiredultrasound image. As such, it is possible to reduce the calculation loadof the ultrasound diagnostic apparatus 1 by calculating the index valuefor the ultrasound image only while the ultrasound probe 2 is in contactwith the body surface of the subject. In addition, in a case in whichthe index value calculation unit 10 calculates the index values, it ispossible to prevent the index value calculation unit 10 from using therecognition scores before the imaging part is changed.

In addition, the index value calculation unit 10 may start thecalculation of the index values for a plurality of parts of the subjectafter a predetermined period of time has elapsed since the probe statedetection unit 13 has detected a change in the imaging part. Forexample, the time until the index value calculation unit 10 calculatesthe index values of the plurality of parts of the subject after theprobe state detection unit 13 detects a change in the imaging part maybe input by the operator through the operation unit 15 or the like, ormay be stored in advance in the storage unit 16.

The time until the ultrasound probe 2 is brought into contact with thebody surface of the subject to obtain the ultrasound image of a targetimaging part varies depending on, for example, the skill of theoperator. In some cases, immediately after the imaging part is changed,an ultrasound image that is sufficiently clear to calculate therecognition score is not obtained. For this reason, in a case in whichthe calculation of the index values of a plurality of parts of thesubject starts after a predetermined period of time has elapsed sincethe probe state detection unit 13 has detected a change in the imagingpart, it is possible to calculate the index values on the basis of aplurality of recognition scores calculated for the ultrasound image thatis sufficiently clear to calculate the recognition scores. Therefore, itis possible to improve the accuracy of calculating the index value.

In addition, in the flowchart illustrated in FIG. 5, Steps S12 and S13may be omitted. In this case, if the determination order in which theimaging part is determined is decided in Step S11, the process proceedsto Step S14. In Step S14, the part determination unit 12 compares therecognition score of the part that ranks first in the determinationorder among the recognition scores of the plurality of parts of thesubject calculated in Step S8 for the latest ultrasound image acquiredin Step S7 with the determination threshold value. At that time, in acase in which the recognition score is equal to or less than thedetermination threshold value, the process proceeds to Step S15.Further, in a case in which it is determined in Step S15 that thethreshold value determination for the recognition scores of all of theplurality of parts of the subject has not been performed in Step S14,the process proceeds to Step S16. In a case in which the determinationpart is updated in Step S16, it is determined in Step S14 whether therecognition score of the part that ranks second in the determinationorder is greater than the determination threshold value.

In the above-described embodiment, the same determination thresholdvalue is used for all of the parts by the part determination unit 12 inStep S14. However, the determination threshold value may be set for eachof the plurality of parts of the subject.

The above-mentioned ultrasound diagnostic apparatus 1 may be a portableultrasound diagnostic apparatus that is small and can be easily carriedand used or a stationary ultrasound diagnostic apparatus that isinstalled and used in, for example, a medical examination room.

In addition, the ultrasound probe 2 is not particularly limited as longas it can transmit and receive ultrasound beams to and from the subjectand may be a sector type, a convex type, a linear type, or a radialtype.

Embodiment 2

In the operation of the ultrasound diagnostic apparatus 1 illustrated inthe flowchart of FIG. 4, in a case in which the ultrasound probe 2 is inthe aerial emission state in Step S6, the process returns to Step S1.Then, in Step S3, the part determination is performed for all of theplurality of parts of the subject. However, the part of the subjectwhich has been decided in Step S3 may be excluded. In this case, it ispossible to further reduce the calculation load of the ultrasounddiagnostic apparatus 1 in the part determination.

FIG. 6 illustrates the operation of an ultrasound diagnostic apparatusaccording to Embodiment 2. Since Steps S1 to S6 in a flowchartillustrated in FIG. 6 are the same as Steps S1 to S6 in the flowchartillustrated in FIG. 4, the detailed description thereof will not berepeated.

In a case in which the probe state detection unit 13 determines that theultrasound probe 2 is in the aerial emission state in Step S6, theprocess proceeds to Step S18. In Step S18, the apparatus control unit 14determines whether all of a plurality of parts of the subject have beendecided. In a case in which it is determined in Step S18 that all of theplurality of parts of the subject have not been decided, the processproceeds to Step S19.

In Step S19, the apparatus control unit 14 excludes the part that hasbeen decided in the part determination of Step S3, that is, the decidedpart from the determination target in the next Step S3. In a case inwhich the process in Step S19 is completed, the process returns to StepS1. Then, in a case in which it is determined in Step S2 that theultrasound probe 2 is not in the aerial emission state, the partdetermination is performed in Step S3. At that time, since the partsother than the part which has been excluded in Step S19 among theplurality of parts of the subject are the determination targets, thenumber of part candidates to be determined for the imaging part can beless than that in the part determination of Step S3 performed for thefirst time.

Steps S1 to S19 are repeated in this way to reduce the number ofdetermination targets. As a result, in a case in which it is determinedin Step S18 that all of the plurality of parts of the subject have beendecided, the operation of the ultrasound diagnostic apparatus ends.

As such, Steps S1 to S19 are repeated to reduce the number ofdetermination targets. Therefore, it is possible to reduce thecalculation load of the ultrasound diagnostic apparatus in the partdetermination of Step S3 whenever Step S19 is performed and to reducethe time required to determine the imaging part.

Embodiment 3

In the part determination operation according to Embodiment 1illustrated in FIG. 5, in the threshold value determination of Step S14,the recognition score of one part of the subject which has beencalculated for the ultrasound image newly acquired in Step S12 by theimage recognition unit 9 is used. However, recognition scores for partdetermination which have been calculated on the basis of the recognitionscores calculated for a plurality of ultrasound images may be used forthe threshold value determination.

FIG. 7 is a flowchart illustrating a part determination operation of anultrasound diagnostic apparatus according to Embodiment 3. The flowchartillustrated in FIG. 7 is the same as the flowchart illustrated in FIG. 5except for Steps S20 to S22.

In the flowchart illustrated in FIG. 7, in a case in which the partdetermination operation starts, first, Steps S7 to S9 are repeated untilthe recognition scores of a plurality of parts of the subject arecalculated for a predetermined number of frames of ultrasound images.Here, the predetermined number of frames is referred to as a firstpredetermined number of frames for the purpose of description. In a casein which it is determined in Step S9 that the recognition scores of theplurality of parts of the subject are calculated for the firstpredetermined number of frames of ultrasound images, the processproceeds to Step S10. In a case in which the index values of theplurality of parts of the subject are calculated from the recognitionscores of the plurality of parts of the subject calculated for the firstpredetermined number of frames of ultrasound images in Step S10, adetermination order is decided in Step S11.

Then, an ultrasound image is newly acquired in Step S12 and the processproceeds to Step S20. Step S20 is the same as Step S8 in the flowchartillustrated in FIG. 5. In a case in which the recognition scores of theplurality of parts of the subject are calculated for the latestultrasound image in Step S20, the process proceeds to Step S21.

In Step S21, the apparatus control unit 14 determines whetherrecognition scores have been calculated for a second predeterminednumber of frames of ultrasound images acquired in Step S12. This is toobtain the number of recognition scores necessary to calculate therecognition scores for part determination. Therefore, in a case in whichit is determined in Step S21 that the recognition scores have not beencalculated for the second predetermined number of frames of ultrasoundimages, the process returns to Step S12 and an ultrasound image is newlyacquired. Then, in Step S20, the recognition scores of the plurality ofparts of the subject are newly calculated.

Here, the first predetermined number of frames in Step S9 and the secondpredetermined number of frames in Step S21 may be equal to or differentfrom each other. For the purpose of description, it is assumed that thefirst predetermined number of frames and the second predetermined numberof frames are different from each other.

In a case in which it is determined in Step S21 that the recognitionscores have been calculated for the second predetermined number offrames of ultrasound images, the process proceeds to Step S22. In StepS22, the image recognition unit 9 averages the recognition scores of thedetermination part that ranks first in the determination order whichhave been calculated for the second predetermined number of frames ofultrasound images in Step S20. As such, the image recognition unit 9calculates the mean value of the recognition scores of the determinationpart as the recognition score for determining the imaging part. In thiscase, it is preferable that a plurality of ultrasound images used torecognize the determination part are continuous in time series.

Then, in Step S14, the apparatus control unit 14 determines whether therecognition score for determination calculated in Step S22 is greaterthan the determination threshold value. In a case in which it isdetermined in Step S14 that the recognition score for determination isequal to or less than the determination threshold value, it is difficultto decide the determination part with respect to the imaging part andthe process proceeds to Step S15. In a case in which it is determined inStep S15 that the threshold value determination for the recognitionscores of all of the plurality of parts of the subject has not beenperformed in Step S14, the determination part is updated in Step S16 andthe process returns to Step S22.

In a case in which the process returns to Step S22, the recognitionscore for determination is calculated for the part that ranks second inthe determination order. As such, as long as the recognition score fordetermination is equal to or less than the determination threshold valuein Step S14, Steps S22 to S16 are repeated. In a case in which it isdetermined in Step S14 that the recognition score for determination isgreater than the determination threshold value, the process proceeds toStep S17 and the imaging part is decided. Then, the part determinationoperation illustrated in the flowchart of FIG. 7 ends.

As such, since the recognition score for part determination iscalculated from the recognition scores calculated for a plurality ofultrasound images, it is possible to improve the accuracy of determiningthe imaging part. For example, even in a case in which a part of thesubject included in some of the ultrasound images acquired in Step S12is not sufficiently clear as the image recognition target, the accuracyof deciding the imaging part is improved.

In the above description, in a case in which the recognition score fordetermining the imaging part is calculated in Step S22, the recognitionscores for the second predetermined number of frames of ultrasoundimages acquired in Step S12 are used. However, the recognition score fordetermining the imaging part may be calculated in Step S22 on the basisof both the recognition scores calculated in Step S20 and therecognition scores for the first predetermined number of frames ofultrasound images. That is, the second predetermined number of framesmay be the sum of the first predetermined number of frames and thenumber of frames of ultrasound images acquired in Step S12.

At that time, in a case in which the second predetermined number offrames is equal to or less than the first predetermined number offrames, that is, in a case in which the number of recognition scores ofa plurality of parts of the subject required to calculate therecognition score for determining the imaging part in Step S22 is equalto or less than the number of recognition scores required to calculatethe index values in Step S10, Step S12, Step S20, and Step S21 can beomitted. Therefore, it is possible to further reduce the time requiredto determine the imaging part.

Embodiment 4

In the part determination operations according to Embodiments 1 and 3illustrated in FIGS. 5 and 7, the determination order in which thethreshold value determination is performed for the recognition score ofeach part of the subject is decided on the basis of the index values ofa plurality of parts of the subject. However, at that time, the parts tobe determined with respect to the imaging part may be narrowed down.

FIG. 8 illustrates the configuration of an ultrasound diagnosticapparatus 21 according to Embodiment 4. The ultrasound diagnosticapparatus 21 according to Embodiment 4 is the same as the ultrasounddiagnostic apparatus 1 according to Embodiment 1 illustrated in FIG. 1except that it includes a part narrowing-down unit 22. Therefore,components other than the part narrowing-down unit 22 are denoted by thesame reference numerals and the detailed description thereof will not berepeated.

In the ultrasound diagnostic apparatus 21 according to Embodiment 4, thepart narrowing-down unit 22 is connected to the index value calculationunit 10. The part narrowing-down unit 22 is connected to the orderdecision unit 11. In addition, the apparatus control unit 14 isconnected to the part narrowing-down unit 22.

The part narrowing-down unit 22 narrows down the parts to be determinedwith respect to the imaging part whose image is currently captured amonga plurality of parts of the subject on the basis of the index values ofthe plurality of parts of the subject calculated by the index valuecalculation unit 10. At that time, the part narrowing-down unit 22narrows down only the parts whose index values are greater than apredetermined value among the plurality of parts of the subject to thedetermination parts.

FIG. 9 is a flowchart illustrating a part determination operation of theultrasound diagnostic apparatus 21 according to Embodiment 4. Theflowchart illustrated in FIG. 9 is the same as the flowchart illustratedin FIG. 5 except that Step S23 substitutes Step S11 in the flowchartaccording to Embodiment 1 illustrated in FIG. 5. Therefore, the detaileddescription of the same steps as those in the flowchart of FIG. 5 willnot be repeated.

In a case in which the part determination operation of the ultrasounddiagnostic apparatus 21 according to Embodiment 4 starts, therecognition scores of a plurality of parts of the subject are calculatedfor a predetermined number of frames of ultrasound images in Steps S7 toS9. Then, in Step S10, index values are calculated on the basis of therecognition scores.

Then, in Step S23, first, the part narrowing-down unit 22 narrows downthe parts to be determined with respect to the imaging part whose imageis currently captured on the basis of the index values of the pluralityof parts of the subject calculated in Step S10. That is, the partnarrowing-down unit 22 narrows down only the parts whose index valuescalculated in Step S10 are greater than a predetermined value among theplurality of parts of the subject to the determination parts. Then, theorder decision unit 11 decides the determination order of a plurality ofparts narrowed down by the part narrowing-down unit 22 such that thepart with a larger index value ranks higher.

Then, in Steps S12 and S13, an ultrasound image is newly acquired andonly the recognition score of a part that ranks first in thedetermination order is calculated. Then, in Steps S14 to S16, it isdetermined whether the recognition score is greater than thedetermination threshold value and the determination part is updated. InStep S16, the determination part is continuously updated. As a result,in a case in which it is determined in Step S15 that the threshold valuedetermination for the recognition scores of all of the plurality ofparts narrowed down in Step S23 has been completed in Step S14, it isdetermined that it is difficult to decide the part included in theultrasound image acquired in Step S12 to be any of the plurality ofparts of the subject and the process returns to Step S8. Then, the partdetermination operation starts again.

In a case in which it is determined in Step S14 that the recognitionscore of the part calculated in Step S13 is greater than the thresholdvalue, the process proceeds to Step S17. In a case in which the part tobe determined with respect to the imaging part whose image is currentlycaptured is decided in Step S17, the part determination operation ends.

As described above, in the part determination operation according toEmbodiment 4, after the parts to be determined with respect to theimaging part whose image is currently captured are narrowed down, thedetermination order is decided. Therefore, the calculation load of theultrasound diagnostic apparatus 21 for deciding the determination orderis reduced. In addition, since the number of determination parts isnarrowed down in Step S20, it is possible to reduce the number of timesthe determination part is updated in Step S16 in a case in which StepsS13 to S16 are repeated. Therefore, according to the ultrasounddiagnostic apparatus 21 of Embodiment 4, it is possible to reduce thecalculation load of the ultrasound diagnostic apparatus 21 and to reducethe time required to determine the imaging part.

The ultrasound diagnostic apparatuses according to the embodiments ofthe invention have been described in detail above. However, theinvention is not limited to the above-mentioned examples and variousmodifications and changes of the invention may be made without departingfrom the scope and spirit of the invention. In addition, a plurality ofembodiments described above may be appropriately combined with eachother.

EXPLANATION OF REFERENCES

1, 21: ultrasound diagnostic apparatus

2: ultrasound probe

2A: transducer array

3: image acquisition unit

4: receiving unit

5: transmitting unit

6: image generation unit

7: display control unit

8: display unit

9: image recognition unit

10: index value calculation unit

11: order decision unit

12: part determination unit

13: probe state detection unit

14: apparatus control unit

15: operation unit

16: storage unit

17: amplification unit

18: A/D conversion unit

19: B-mode processing unit

20: image processing unit

22: part narrowing-down unit

What is claimed is:
 1. An ultrasound diagnostic apparatus comprising: anultrasound probe; a transmission circuit configured to transmit anultrasound beam from the ultrasound probe to a subject; a receptioncircuit configured to receive ultrasound echoes from the subject by theultrasound probe to generate element data; and a processor configured togenerate an ultrasound image on the basis of the element data generatedby the reception circuit, perform image recognition for the ultrasoundimage generated to calculate recognition scores of a plurality of partsof the subject, calculate index values of the plurality of parts on thebasis of the recognition scores of the plurality of parts calculated fora predetermined number of ultrasound images, decide a determinationorder in which part determination is performed for the plurality ofparts on the basis of the index values, and determine an imaging part ofthe subject on the basis of the recognition scores according to thedetermination order.
 2. The ultrasound diagnostic apparatus according toclaim 1, wherein the processor uses, as the index values of theplurality of parts, recognition scores of the plurality of partscalculated for a latest ultrasound image acquired.
 3. The ultrasounddiagnostic apparatus according to claim 1, wherein the processorcalculates the index values of the plurality of parts on the basis ofrecognition scores of the plurality of parts calculated for each of aplurality of ultrasound images which are continuously acquired in timeseries and include a latest ultrasound image acquired.
 4. The ultrasounddiagnostic apparatus according to claim 3, wherein the processor usesmean values or medians of the recognition scores of the plurality ofparts calculated for the plurality of ultrasound images as the indexvalues of the plurality of parts.
 5. The ultrasound diagnostic apparatusaccording to claim 3, wherein the processor uses maximum values orminimum values of the recognition scores of the plurality of partscalculated for the plurality of ultrasound images as the index values ofthe plurality of parts.
 6. The ultrasound diagnostic apparatus accordingto claim 3, wherein the processor calculates weighted mean values of therecognition scores of the plurality of parts by giving a larger weightto an ultrasound image more recently acquired among the plurality ofultrasound images and uses the weighted mean values as the index valuesof the plurality of parts.
 7. The ultrasound diagnostic apparatusaccording to claim 3, wherein the processor gives ranking scores to theplurality of parts for each of the plurality of ultrasound images suchthat the part with a higher recognition score has a higher ranking scoreand uses sums of the ranking scores of the plurality of parts for theplurality of ultrasound images as the index values of the plurality ofparts.
 8. The ultrasound diagnostic apparatus according to claim 3,wherein the processor has a threshold value of the recognition score anduses the number of recognition scores greater than the threshold valueamong the recognition scores of the plurality of parts calculated forthe plurality of ultrasound images as the index value of each of theplurality of parts.
 9. The ultrasound diagnostic apparatus according toclaim 3, wherein, in a case in which there are the same index valuesamong the calculated index values of the plurality of parts, theprocessor calculates the index values again, using an ultrasound imagegroup which includes the latest ultrasound image and consists ofultrasound images which are continuous in time series and whose numberis less than the number of the ultrasound images used to calculate theindex values.
 10. The ultrasound diagnostic apparatus according to claim4, wherein, in a case in which there are the same index values among thecalculated index values of the plurality of parts, the processorcalculates the index values again, using an ultrasound image group whichincludes the latest ultrasound image and consists of ultrasound imageswhich are continuous in time series and whose number is less than thenumber of the ultrasound images used to calculate the index values. 11.The ultrasound diagnostic apparatus according to claim 5, wherein, in acase in which there are the same index values among the calculated indexvalues of the plurality of parts, the processor calculates the indexvalues again, using an ultrasound image group which includes the latestultrasound image and consists of ultrasound images which are continuousin time series and whose number is less than the number of theultrasound images used to calculate the index values.
 12. The ultrasounddiagnostic apparatus according to claim 6, wherein, in a case in whichthere are the same index values among the calculated index values of theplurality of parts, the processor calculates the index values again,using an ultrasound image group which includes the latest ultrasoundimage and consists of ultrasound images which are continuous in timeseries and whose number is less than the number of the ultrasound imagesused to calculate the index values.
 13. The ultrasound diagnosticapparatus according to claim 3, wherein, in a case in which there arethe same index values among the calculated index values of the pluralityof parts, the processor calculates the index values again, using anultrasound image group consisting of a plurality of ultrasound imageswhich are continuous in time series and are acquired before the latestultrasound image in time series.
 14. The ultrasound diagnostic apparatusaccording to claim 4, wherein, in a case in which there are the sameindex values among the calculated index values of the plurality ofparts, the processor calculates the index values again, using anultrasound image group consisting of a plurality of ultrasound imageswhich are continuous in time series and are acquired before the latestultrasound image in time series.
 15. The ultrasound diagnostic apparatusaccording to claim 5, wherein, in a case in which there are the sameindex values among the calculated index values of the plurality ofparts, the processor calculates the index values again, using anultrasound image group consisting of a plurality of ultrasound imageswhich are continuous in time series and are acquired before the latestultrasound image in time series.
 16. The ultrasound diagnostic apparatusaccording to claim 6, wherein, in a case in which there are the sameindex values among the calculated index values of the plurality ofparts, the processor calculates the index values again, using anultrasound image group consisting of a plurality of ultrasound imageswhich are continuous in time series and are acquired before the latestultrasound image in time series.
 17. The ultrasound diagnostic apparatusaccording to claim 1, wherein the processor detects a change in theimaging part caused by movement of the ultrasound probe and starts tocalculate the index value after detecting the change in the imagingpart.
 18. The ultrasound diagnostic apparatus according to claim 1,wherein the processor decides the determination order such that the partwith a larger index value ranks higher.
 19. A method for controlling anultrasound diagnostic apparatus, the method comprising: transmitting anultrasound beam from an ultrasound probe to a subject to generate anultrasound image; performing image recognition for the ultrasound imageto calculate recognition scores of a plurality of parts of the subject;calculating index values of the plurality of parts on the basis of therecognition scores of the plurality of parts calculated for apredetermined number of ultrasound images; deciding a determinationorder in which part determination is performed for the plurality ofparts on the basis of the index values; and determining an imaging partof the subject on the basis of the recognition scores calculatedaccording to the determination order.
 20. A readable recording mediumrecording a program for controlling an ultrasound diagnostic apparatus,the program causing a processor to perform: a step of transmitting anultrasound beam from an ultrasound probe to a subject to generate anultrasound image; a step of performing image recognition for theultrasound image to calculate recognition scores of a plurality of partsof the subject; a step of calculating index values of the plurality ofparts on the basis of the recognition scores of the plurality of partscalculated for a predetermined number of ultrasound images; a step ofdeciding a determination order in which part determination is performedfor the plurality of parts on the basis of the index values; and a stepof determining an imaging part of the subject on the basis of therecognition scores calculated according to the determination order.